Like Mireille mentions if you open your Replay you will have a slot for an mSATA drive. My one Replay has a KingSpec I think the brand is mSATA in it. This is the brand that would have come in one installed by DreamArcades.

While looking up the brands to reply to your post here I noticed that these USB C to SATA enclosures are a thing. The bottom of the Replay has a USB C port that acts like a SATA port.

I do not know if these will work. I just happened to notice they exist. If you were to try it you would have to turn your Replay upside down since the port is on the bottom.

If you are having a software problem be it front end, Windows, or want to try RetroArch and LauchBox but need help feel free to contact me. Post on the forum, PM here, or on Discord. I will be more then happy to do my best to get you sorted.

If you mean you want to try something like that enclosure I mentioned then the largest size is a 2TB 2.5 inch drive. A 3TB 2.5 inch drive is a few mm bigger (15mm over all), and it will not fit in a stock Replay bay or that enclosure linked above

If you are having a software problem be it front end, Windows, or want to try RetroArch and LauchBox but need help feel free to contact me. Post on the forum, PM here, or on Discord. I will be more then happy to do my best to get you sorted.

Yeah I really do not want a standalone drive. Too many cable and power supplies to deal with when traveling.

really wish I would have gotten the add-on accessory drive kit when available as no one has one for sale except the foreign amazon sites that do not ship to US.

The Internal mSATA slot would be nice to use as it keeps the overall unit small but only 1TB and at around $170 makes it last option choice for me. May just wait a little while and see if the accessory drive bays come back in stock.